Value perception dominates color perception.
Notes from Wikiquote
III. The rules of the graphic system
There are as many types of questions as components in the information.
The aim of the graphic is to make the relationship among previously defined sets appear.
Quote text and notes from Wikiquote: Jacques Bertin (page history), available under CC BY-SA 4.0. Source quality and labels are our own summary of what Wikiquote records.